<template>
  <view>
    <!-- 使用自定义的搜索组件 -->

    <view class="search-box">
      <my-search @click="gotoSearch"></my-search>
    </view>

    <!-- 滚动视图 -->
    <view class="scroll-view-container">
      <!-- 左侧的滚动视图区域 -->
      <scroll-view class="left-scroll-view" scroll-y :style="{ height: wh + 'px' }">
        <block v-for="(item, i) in cateList" :key="i">
          <view :class="['left-scroll-view-item', i === active ? 'active' : '']" @click="activeChanged(i)">
            {{ item.cat_name }}
          </view>
        </block>
      </scroll-view>

      <!-- 右侧的滚动视图区域 -->
      <scroll-view class="right-scroll-view" scroll-y :style="{ height: wh + 'px' }" :scroll-top="scrollTop">
        <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
          <view class="cate-lv2-title">{{ item2.cat_name }}</view>
          <!-- 动态渲染三级分类的列表数据 -->
          <view class="cate-lv3-list">
            <!-- 三级分类 Item 项 -->
            <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <!-- 图片 -->
              <image :src="item3.cat_icon"> </image>
              <!-- 文本 -->
              <text>{{ item3.cat_name }}</text>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>

export default {
  name: "MobileShoppingCate",
  data() {
    return {
      wh: 0,
      cateList: [],
      cateLevel2: [],
      active: 0,
      scrollTop: 0,
    };
  },

  onLoad() {
    //  获取当前系统的信息
    const sysInfo = uni.getSystemInfoSync();
    // 为 wh 窗口可用高度动态赋值
    this.wh = sysInfo.windowHeight;

    /* ==================================== */
    this.getCateList();
  },

  methods: {
    /**
     * 获取分类列表
     */
    async getCateList() {
      // 发起请求
      const { data: res } = await uni.$http.get("/api/public/v1/categories");
      // 判断是否获取失败
      if (res.meta.status !== 200) return uni.$showMsg();
      // 转存数据
      this.cateList = res.message;
      // 为二级分类赋值
      this.cateLevel2 = res.message[0].children;
    },

    /**
     * 选中项改变的事件处理函数
     * @param {cateList.id} 被点击项 ID
     */
    activeChanged: function (i) {
      this.active = i;
      // 为二级分类列表重新赋值
      this.cateLevel2 = this.cateList[i].children;
      // 让 scrollTop 的值在 0 与 1 之间切换
      this.scrollTop = this.scrollTop === 0 ? 1 : 0;
    },

    /**
     * 点击三级分类项跳转到商品列表页面，跳转该项
     * @param {*} item 被点击项
     */
    gotoGoodsList: function (item) {
      uni.navigateTo({
        url: "/subpkg/goods_list/goods_list?cid=" + item.cat_id,
      });
    },

    /**
     * 跳转搜索子页面
     */
    gotoSearch() {
      uni.navigateTo({
        url: "/subpkg/search/search",
      });
    },
  },
};
</script>

<style lang="scss" scoped>
// 左右两栏滚动
.scroll-view-container {
  display: flex;

  .left-scroll-view {
    width: 120px;

    .left-scroll-view-item {
      line-height: 60px;
      background-color: #f7f7f7;
      text-align: center;
      font-size: 12px;

      /* 激活项的样式 */
      &.active {
        background-color: #ffffff;
        position: relative;

        /* 渲染激活项左侧的红色指示边线 */
        &::before {
          content: " ";
          display: block;
          width: 3px;
          height: 30px;
          background-color: #c00000;
          position: absolute;
          left: 0;
          top: 50%;
          transform: translateY(-50%);
        }
      }
    }
  }
}

// 二级标题样式
.cate-lv2-title {
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 15px 0;
  font-size: 16px;
  color: white;
  background-color: #c00;
  margin: 10px;
}

/* 美化三级分类 */
.cate-lv3-list {
  display: flex;
  flex-wrap: wrap;

  .cate-lv3-item {
    width: 33.33%;
    margin-bottom: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;

    image {
      width: 60px;
      height: 60px;
    }

    text {
      font-size: 12px;
    }
  }
}
</style>
